A New Species of the Genus Rhogeessa, with Comments on ...
University of Nebraska - Lincoln
DigitalCommons@University of Nebraska - Lincoln Mammalogy Papers: University of Nebraska State Museum
Museum, University of Nebraska State
1996
A New Species of the Genus Rhogeessa, with Comments on Geographic Distribution and Speciation in the Genus Hugh H. Genoways University of Nebraska - Lincoln, [email protected]
Robert J. Baker Texas Tech University, [email protected]
Follow this and additional works at: http://digitalcommons.unl.edu/museummammalogy Part of the Biodiversity Commons, Other Ecology and Evolutionary Biology Commons, and the Zoology Commons Genoways, Hugh H. and Baker, Robert J., "A New Species of the Genus Rhogeessa, with Comments on Geographic Distribution and Speciation in the Genus" (1996). Mammalogy Papers: University of Nebraska State Museum. Paper 248. http://digitalcommons.unl.edu/museummammalogy/248
This Article is brought to you for free and open access by the Museum, University of Nebraska State at DigitalCommons@University of Nebraska Lincoln. It has been accepted for inclusion in Mammalogy Papers: University of Nebraska State Museum by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln.
From Contributions in Mammalogy: A Memorial Volume Honoring Dr. J. Knox Jones, Jr., edited by Hugh H. Genoways and Robert J. Baker. Copyright 1996, Museum of Texas Tech University. Used by permission.
A NEW SPECIES OF THE GENUS RHOGEESSA,
WITH COMMENTS ON GEOGRAPHIC DISTRIBUTION AND SPECIATION IN THE GENUS Hugh H. Genoways and Robert J. Baker A new species of Rhogeessa is described from southern Suriname. The new species is characterized by a karyotype that possesses a diploid number of 52 and a fundamental number of 52 and by its relatively large overall size comparedto other SouthAmerican Rhogeessa. Tenspecies are now recognized within the genus. Seven of these species, including the one described herein, are members of R. tumida complex. Two of these species - R. io and R. minutilla - also occur in South America and the remaining four species are confined to Mexico and Central America. ABSTRACT . -
Key words: Rhogeessa, Suriname, karyology, systematics, Mammalia Bats of the genus Rhogeessa ha ve pre sented evolutionary biologi sts and systematists with a unique suite of features . Several cryptic or sibling species are identified by karyotypic variation (Baker, 1984 ; Baker et aI., 1985) and thi s complex has been used as an empirical basis for a speci atio n mod el (spec iation by mo nobrachi al fusi on s, Baker and Bickham , 1986 ). Some species show little orno morphological distinctiveness (Baker, 1984). For the two most widely distri but ed speci es recognized by morphologica l differenc es (R. tumida and R.parvula), the rang e of geographic vari ation in morph ology within both species is greater than any morphological features that distinguish the two (La Val, 1973). Although, several species h ave been recognized based on kary otypes, the morphological feature s are still problematic when used to identify taxa. One of the karyotypic form s (Ho neycutt et al., 1980 ) from Suriname has been identified as a previously undescri bed species (Ruedas and Bickham, 1992) and this paper present s a formal description of that taxon . Be fo re a formal de script ion can be m ade , so me clarificati on of speci es boundaries and characteristics is needed to permit the required comparisons. This undescribed spec ies is a member of the R. tumida complex in South America. The first point to consider is that other specimens of the R. tumida complex that have been karyotyped from South America have a diploid number of 30. Specimens with this karyotype have been G-banded and cladistically analyzed (Bak er et aI., 1985) using Myotis and Eptesicus
as out groups (Bic kham , I 979a ; 1979b). The results of thi s analysis indicated that th e 2N = 30 cytotype fr om South America and 2N = 32 cyt otype from Nicaragu a represent sister clades identified by three unique centric fu sions (5/1 , 10/4 , and 11/7 using the sta nda rdized GBand karyotyp e f o r ve spertili onid b ats , Bi c kham , I 979a ). Ba sed on the potential complex meiotic figures that would result from hybrids betw een either the 2N = 30 or the 2N = 32 (N icaraguan) cytoty pes and any ot her cytotype found north of South America, it is probable that the 2N = 30 and 32 (N icaragu an form ) hav e speci ated from more northern taxa by monobrachial fu sions (Baker and Bickham, 1986). The senior sy nony m for the 2N = 30 and 32 (N icar agu an f orm ) cytot ype s is R. i o Tho ma s, 1903 , with a typ e locality of Valencia, Carabobo , Venezuela. At this time it seems appropriate to consider the 2N = 30 cytotype and the 2N = 32 (Nicara guan form ) as co nspeci fic becau se there is no ev idence of an isolating mechanism in the chromoso mal or other data . Therefore, the ran ge of R. i o should be recogni zed as the Atlantic versant of Nicaragua south thr ough Panama, and South America including specimens of R. tumida rec orded by LaVal ( 197 3) for Colomb ia , Venezuel a, Trini da d, Gu yana , and Mato Grosso, Brazil. The situation surro unding the Ecuador specimens is unclear (LaVal , 1973 ; Goodwin , 1958 ). La Val examined and figured bacula (197 3, Fig 2, p. 9) for se veral representatives of the R. tumida com-
Pp. 83 - 87, Contr ibutions in Mammal ogy: A Memori al Volume Honoring Dr. 1. Knox Jones , Jr. Museum of Texas Tech Univ ersity, 1996, il + 3t5 pp.
1. KNOX JON ES MEMORIAL VOL UME
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plex . Three specimens (fro m Veracru z, Tamaulipas, and Chiapas) are from the ran ge of the 2N = 34 cytotypes (w mida , sensu stricto) and these three are more simi lar to each o ther than to any of the re maining bacula that are figured. Three o ther specime ns , th e eastern versant of Nicarag ua , Co lombia , and Venez ue la , are fro m our pro posed range for R. io and these thr ee have unique bacular morp hology unlike that seen in tumida (senso stricto) and these three are more lik e each other than any is like rep resentatives of tumida (se nsu stric to) . To our eye the baculu m of th e sp eci me n fro m Pun a Isl an d, Ec uado r, m ost c losely resembles th e b acul a of R . minutilla. It is interes tin g to n o te th at R . minutilla is a coast al and island form in the xeri c region s of Venezuel a and Colomb ia and the Puna Island locality matches well this eco logical situatio n . Th er efo re , we are un c om fortable assigning th e Ecua dor specimens to a specific taxon and more study is needed . Chro m osoma l dat a fro m bo th R . minutilla an d th e Ec uad o r p opu lat ion sh ould be va lu a ble in es ta blishing the se rel ation shi ps. We thi nk that th ere are ten s pec ies in the gen us Rhogeessa that sho uld be recognize d. Rhogeessa alieni and R. gracilis are the o utliers rel at ive to the other spec ies and R . mira m ay we ll be as distant to the rema ining tax a as are R. alleni a nd R. gra cilis (La Val, 1973 ). The
relationsh ip of alleni , gracilis , and mira to each other and to m ember s of th e R . tu mi da compl e x m e rit s f urt he r study. Withi n wh at we wi ll ca ll the R. tum ida co mplex there are seven species . Rhogeessa tumida is di stribut ed along the Atlantic versa nt of Mexico so uth ward to Ho nduras wh er e it is found on both the Pa ci fic and A tlan tic versants , Rh ogeessa parv ula is di stributed in M exico f ro m S o n o r a to Guerrero a n d Oax a c a . Rhogeessa ge nowaysi is kn own fro m a re st ri ct ed are a in Chi apas, Mexico. The di stribution of Rhogeessa io is as descr ibed above . The 2N = 32B form de scribed by Ba ker et al. (1 985 ) fro m Belize has been show n to occur in Beli ze , north ern Guatem ala, and throughout th e Yucatan Peninsula by Aude t et al. ( 1993). The seni or syn on ym applied t o thi s taxon was Rh ogeessa aeneus Goodwin , 195 8 (Aude t et aI., 1993). Rho geessa minutilla is found alon g th e no rth co as t of South Ame rica on Margarita Is land, Venezuela , and Co lom bia. The spec ies w e are descri bing herein is fro m northeast ern So uth A mer ic a. The geo graphic relationship of these taxa can be seen in Fi gure I and Bake r ( 1984 ). An ov erview of th e geographic di stribution of the tumida co mp lex indi cates tha t areas of sy rnpatrv are unco mmon and parapatry may be the common rela tions hip at species boundarie s. Our wo rking hy po the s is I S that
~l
()- )
R. tumida
-:«:
--;:;'--R. aeneus
o
~
"
~
c::::>e. zone of
R.
'.. overlap
R.
R. minuti/la .
/ " R. 10
-b..f]
~~~~~
Fig. I. Approxi mate geog raphic distribution of the seve n speci es in the Rhogeessa lumida - co mplex . Exac t geog ra phic boundaries and area s of pot ential sym patry betwee n species arc ye t to be fully studied. Reco rds from Brazil and Ecuador arc not show n (see text and La Val. 1973).
GENOWAYS AND BAKER- NEW RHOGEESSA
85
this pattern is the result of speciation of a once wide spread single species and the relationships among species will in most cases reflect geographic associations. When the geographic di stribution of the R. tumida complex is contrasted with that observed for the other vespertilionid gener a such as Myotis, Lasiurus , and Ep tesicus , the pattern seen in Rhogeessa appears exceptional. In the former three genera, sympatry among species is common and examples of parapatry are not well docum ented . The new taxon described below is from Suriname in northeastern So uth America and the species of Rhogeessa that are in a geographic position to hybridize with the new species are R . i o defin ed above and R. minutilla from along the coast of Venezuela and Colombia.
Rhogeessa hussoni, new species Holotyp e.-Adult femal e, skin and skull , Carnegie Mu seum of Natural History no. 63934, from Surin ame: Nickcric District; Sipaliwini Airstrip; obtained on 18 August 1979 by Jane A . Gr oen and Stephen L. William s; original no. Jane A. Groen 1058; special no . TK 10150. Distributioll. -Northea stern South America (Fig . I ). Known with certa inty from only two localities, one in extreme southwestern Suriname in Nickerie District and the othe r from the state of Bahia in northeastern Bra zil. However, the spec imen from Alto Parnaiba, Maranhao , Brazil , reported by Goodwin ( 1958) and LaVal (19 73 ) may best be assigned to thi s spec ies. It is a skin only in the Fi el d Museum with a length o f fo re ar m of 29.5 (Goo dwi n, 195 8) which is lar ger than any R . min willa (Ruedas and Bickham , 1992) and at the upper end of the variation of R. io. On the other hand , measurements for specimens from southern Guyana (LaVal, 1973) are relatively sm all and we cont inue to ass ign them to R. io until more info rma tion, parti cularly karyotypes, are avai lable from this area. Se lected measurements . -The following external measurements (in millimeters) of the holotype follow those of Ruedas and Bickham (1992 ): length of forearm, 30.2; metacarp al of digit 3,29.0; first (proximal) phalanx of digit 4,27 .8; first phal anx of digit 4, 9.3; metacarpal of digit 5, 28.2; first phalanx of digit 5,7.3. Cran ial measurements (in millim eters ) of the hol otype (Fig. 2) and a sub adult female from Bahia, Brazil (CM 100,000 ), aft er Ruedas and Bickham ( 1992) are as follows : breadth of braincase , 5.7 , 5 .5; condylobasal length , 10 .0 , 9.1 ; depth of braincase , 4.7,4 .6 ; greatest length of sku ll, 13.2 , 12.8 ; mast oid breadth, 7.1, 6 .8; length of mandibular toothrow, 5.2. 5.2; length of maxil-
Fig.2 . Dorsal , ventral, and lateral views ofthe crani um and latera l view of the mandible of the fem ale holotype of Rhoge essa hussoni from Sur iname (e M 63934 ). Bar equal s 5 mm .
lary toothrow, 4.7, 4.5; postorbital breadth, 3.2. 3.2: postpalat al length, 4.7, -; width across upper canines, 3X 3.7: width acro ss upper molars, 5.6, 5.5: zyg omatic breadth , 8.9, -. Diagnosis .-D ipl oid number eq ua ls 52 (Fig. 3 ) with a fundamental number of 52 . Size relatively large compared to other South American species of the genus Rhogeessa with a pr op orti onally s ho rt m andibul ar toothrow. Co mpariso ns ---R hogeessa hussoni is d i s t i nguished by having a diploid number 52 from other members of the genus for which the karyotype is known , includingRhogeessa genowaysi 2N=42 , R. parvula 2N=44 , R. io 2N=30,32, R . tumida 2N=34, and R. aeneus 2N = 32. La Val ( 1973) cite s sev eral char acters by which Rhogeessa minutilla an dR. tumida [=io ] can be di st inguished in northwestern Venezuela. The hol otype of R. hussoni fits several of the characters of R. io mor e clo sely than R. minutil/a. Among these characters are lack of a "helmet" on the cranium, postorb ital breadth of 3.2, teeth unworn , and the third met acarpal more than 1 mm shorter than the forearm .
1. KNOXJONES MEMORIAL VOLUME
86
... t'~~. A. .A...
-.
A
•• r, It ft 1
"
,...
n
AI
•••• ••
Fig ,3 , Representative karyotype of the female holotype of Rhogeessa hussoni from Suriname (e M 63934). The first pair of biarmed chromosomes arc assumed to bethe X -chromosomes. This figure is reprinted from Honeycutt et al ., 1980.
Overall size is largecompared to the other two South American species of the genus , R. minutilla and R. io , except that the length of the mandibular toothrow is proportionally and actually shorter than in these two specie s. The external measurements of the holotype exceed the range of variation in a series of nine R. minutilla and l OR. in [under the name tumidai (Ruedas and Bickham , 1992 ) in four of the eight measurements studied including (range for R. minutilla followed by R . io ) metacarpal of digit 3 (25.7-28.0; 26.2-28.4 ), second phalanx of digit 3 (8.7-10 .2; 8.8-10 .0) , metacarpal digit 4 (25. 1-27 .6; 25 .9-2 7.4 ), and metacarpal of digit 5 (26.0-27.9; 26.327.8). The cranial measurements of the holotype exceed the range of vari ation of thes e same series in five of the II mea surements studied including cond ylobasallength (8 7-9.8: 8.5-91 ), greatest length of skull (11.8-12 .9 ; 11.7-12 .6), postpaJatallength (4.1-4.4; 4.0-4.4), width across upper canin es (3.3-3.7; 3.4-3.6), and width across upper mol ars (5.0-5.5; 5.0-5.4 ). On the other hand , the length of the mand ibular toothrow of the holotype is 5.2 whi ch is under the range of variation in these samples (5.3 -6 .0; 5.4-5 .7 ) presented by Ruedas and Bickham (1992) . The specimen examined from Brazil is a subadult female with the ph alangeal epiph yses still clearly open. There is not a kary otype avail able for this specimen, but we ha ve assigned it to R. hussoni because of its short mandibul ar toothrow which is fully erupted . Remarks .-Diploid numbers reported for the Rhogeessa tumida complex are 30 , 32 , 34 , 42, 44 , and 52 (Bickham and Baker, 1977; Baker, 1984; Honeycutt et ai, 1980). When described, five of these values (30, 32, 34, 42, and 52) were reported for what at that time was recog-
nized as a single species, R . tumida. Part of the variation within tumida was removed when Baker (1984) described the 2N = 42 form as R. ge nowaysi. The ju stification for specific distinctiveness of the 2N = 42 form was the sympatric occurrence of the 2N = 42 and the 2N = 34 forms . The 2N = 34 cytotype is widely distributed and includes the type locality of tumida, whereas the 2N = 42 cytotype is restricted to a small geographic region in Chiapas, Mexico. Without chromosomal data , the existence of R. genowaysi would not ha ve been detected, as exhaustive examinations of the two have failed to provide morphological feature s or measurements to distinguish between them (1. K. Jones, Jr., and D. C. Carter, pers. comm .). The description of the 2N = 52 cytotype herein , does not have the clear cut situation established by sympatric occurrence . However, se veral aspect s o f the karyotypic data from South American taxa indicate it is appropriate to describe R. hussoni at the specific level. Over one hundred species of vespertilionid bats have been karyotyped (McBee et al., 1986) and certain pattern s are evident. For this family the primiti ve karyotype is prop osed to be 2N = 44 with a G-band karyotype like that found in most Myotis (Bickham, 1979a , 1979b ). For species with a higher diploid number like Eptesi cus fliS CUS , centric fissions are proposed to have occurred. Such a series of fis sions are required to deri ve the propo sed karyotype primiti ve for Rhogeessa (Baker et al ., 1985 ). Baker et al. (1985) proposed that two biarmed autosomes (the 16/1 7 and the 20/18) and a biarmed X were present in the karyotype primitive for Rhogeessa . They proposed that the 20/18 was a synapomorphy for the genus , however, the 16/17 was primitive for all vespertilionids. Becau se we have karyotyped only a female for R. hussoni and no G-bands ha ve been produced we arc forced to estimate the evolution of the karyot ype fro m nondifferentiall y stained chromosomes. We suspect that the large biarmed element in R. hussoni is the X and the two other s m a l l e r biarmed clements are lik ely autosomes. If one of the small er elements is the 20/18 then other events are required to derive the R . hussoni karyotype from that proposed as primiti ve for Rhogeessa . These events are likely the fission of the 16/17 or 20/18 and the fragmentation of one other acrocentric to elevate the karyotype to a 2N = 52. Perhaps, both the 20/18 and the 16/17 arc fissioned and the two other biarmed autosome s are from pericentric inver sions . Unfortunately, all of this is speculation, but , it is clear that several events are required to produ ce the R. hus soni karyot ype
GENOWAYS AND BAKER- NEW RHO GEESSA
from that proposed as primitive for Rhogeessa and several event s are required to relate the R. hussoni karyotype to that known for any de scribed for an extant species . Therefore , the most con servati ve cour se of action is to describe R. hussoni as a distinct species. In fact , if we were to describe R. hussoni as a subspecies based on the available chromosomal data , we would not know in which recogni zed species to place it. Etymology.- It is our pleasure to name this species in honor of the late Dr. A. M. Husson, the former Curator of Mammal s of the Rijksmuseum van Natuurlijke Historie in Leiden, The Netherlands, in recognit ion of his maj or contributi on s to the s tudy of So uth American mammal s through his monographs on the bats of Suri name (1962) and the mamm als of Suriname (1978). Spe cim ens examined (2).- Suriname: Nickerie District; Sipaliwin i A irstrip I (CM). Brazil: Bahia; FazendaS ao Raimund o, Juazeiro da Bahia, I (C M). ACKNOWLEDGMENTS .-We wo uld particularl y like to thank Dr. Duane A. Schlitter, Carnegie Museum of Natural History (CM), for the loan of specimens for our examination. Our field work in Suriname was supported by a grant from the Alc oa Foundation, Pittsburgh , PA. We would also like to thank Dr. Joop P. Schulz and Henry A. Reich art. STINA SU. for assistance in all phase s of our work in Su riname. Ferdi nand L. Baal, Department of Forestry, issued our permits. Mr. Leo Roberts. STINAS U, proved to be an exce llent field guide and most congenial companion. Stephen L. William s and Jane A. Groen conducted much ofthe field workin Suriname. Laboratory phase s of this work were supported by an NSF grant to Robert J. Baker. Finally. we want to thank John W. Bickham, Meredith J. Hamilton, and J. Knox Jones. Jr., for reviewing a draft of this manuscript.
liTERATURE CITED
Audet , D., M. D. Engstrom, and M. B. Fent on. 1993. Morph ology, karyology, and echolocation calls of Rh ogeessa (Chiroptera: Vesp ertili on idae ) fro m the Yucatan Peninsula. Journal of Mammalogy, 74:498-502.
87
Baker, R. J. 1984. A sympatric cryptic species of mamm al: a new species of Rhog eessa (Chiroptera: Vespertilionidae ). Systematic Zoolog y, 33: 178-183. Baker, R. J., and J. W. Bickham. 1986. Speciati on by monobrachial cen tri c fusion s. Proceedings of the National Academ y of Science, USA, 83: 8245-8248. Baker, R. J., J. W. Bickham, and M. L. Arnold . 1985 . Chromosomal evolution in Rhogeessa: pos sible speciat ion by centric fusio ns. Evolution, 39: 233-243 . Baker, R. J., M. B. Qums iyeh, and C. S. Hood . 1987. Role of chromo somal banding patterns in understanding mammalian evoluti on . Pp . 67- 96 , inCurrent Mamm al o gy ( H . H . Genoways, ed.), Plenum Press, New York, l :xx+I -519. Bickham , J. W. 1979a. Banded karyotypes of II species of American bats (ge nus Myo tis). Cytologia, 44: 19-27 . - - - . 1979b. Chromosomal variation and evolut iona ry relationshi ps o f vespertilionid bat s . Journ al o f Mam mal og y, 60:350-363. Bickham , J. W., and R. 1. Baker. 1977 . Implicati ons of chromosomal variatio n in Rhogeessa (Chiroptera : Vespertil ionid ae). Journ al of Mammalogy, 58:44 8-4 53. Goodwin, G . G . 1958 . Bat s of the genus Rh oge essa. A merican Museum Novitates, 1923: 1-17. Honeycutt , R. L., R. J. Baker, and H. H. Gen owa ys. 1980. Results of the Alcoa Foundation - Suriname Exped itions. III. Chromos omal data for bats (Mammalia: Chiroptera ) from Suriname . Annal s of Carnegie Museum , 49: 237-250. Husson, A. M. 1962. The bats of Suriname. Zoologische Verhandelingen, Rijk smuscum Natuurlijkc Historic, Leidcn. 58: 1282. - - - . 1978. The mammals ofS urinamc. Zoo logi sche Monograph i cn , Rijksmuseum N atuurlijkc Histor ic , Le idc n. 2:xxxiv+1-569 . LaVal, R. K. 1973 . Systematics ofthc genu s Rhogeessa (C hiroptera: Vespertilionidac). Occasional Papers of the Muscum of Natural History, University of Kansas, 19:1-47 . McBee, K., 1. W. Bickham. S. Ycnbutra. J. Nab hitabhata. and D. A. Schlitter. 1986. Standard karyo logy of nine species of' vespcrtil ion id bats (Chiroptcra : Vespertilion idae ) from Thailand . Annal s of Carnegie Museum , 55:95- 116. Rucdas, L. A., and 1. W. Bickham . 1992. Morph ological differen tiation between Rh ogeessa minutilla and R. tumida (Ma mmalia: Chiroptera : Vespertilionidac). Proce edings of the Biological Society of Washington, 105 : 403-40 .
University ofNebraska State Museum, W436 Nebraska Hall, University of Nebraska-Lincoln, Lincoln, NE 68588-0514 .. Department ofBiological Sciences and The Museum, Texas Tech University, Lubbock, TX 79409.
DigitalCommons@University of Nebraska - Lincoln Mammalogy Papers: University of Nebraska State Museum
Museum, University of Nebraska State
1996
A New Species of the Genus Rhogeessa, with Comments on Geographic Distribution and Speciation in the Genus Hugh H. Genoways University of Nebraska - Lincoln, [email protected]
Robert J. Baker Texas Tech University, [email protected]
Follow this and additional works at: http://digitalcommons.unl.edu/museummammalogy Part of the Biodiversity Commons, Other Ecology and Evolutionary Biology Commons, and the Zoology Commons Genoways, Hugh H. and Baker, Robert J., "A New Species of the Genus Rhogeessa, with Comments on Geographic Distribution and Speciation in the Genus" (1996). Mammalogy Papers: University of Nebraska State Museum. Paper 248. http://digitalcommons.unl.edu/museummammalogy/248
This Article is brought to you for free and open access by the Museum, University of Nebraska State at DigitalCommons@University of Nebraska Lincoln. It has been accepted for inclusion in Mammalogy Papers: University of Nebraska State Museum by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln.
From Contributions in Mammalogy: A Memorial Volume Honoring Dr. J. Knox Jones, Jr., edited by Hugh H. Genoways and Robert J. Baker. Copyright 1996, Museum of Texas Tech University. Used by permission.
A NEW SPECIES OF THE GENUS RHOGEESSA,
WITH COMMENTS ON GEOGRAPHIC DISTRIBUTION AND SPECIATION IN THE GENUS Hugh H. Genoways and Robert J. Baker A new species of Rhogeessa is described from southern Suriname. The new species is characterized by a karyotype that possesses a diploid number of 52 and a fundamental number of 52 and by its relatively large overall size comparedto other SouthAmerican Rhogeessa. Tenspecies are now recognized within the genus. Seven of these species, including the one described herein, are members of R. tumida complex. Two of these species - R. io and R. minutilla - also occur in South America and the remaining four species are confined to Mexico and Central America. ABSTRACT . -
Key words: Rhogeessa, Suriname, karyology, systematics, Mammalia Bats of the genus Rhogeessa ha ve pre sented evolutionary biologi sts and systematists with a unique suite of features . Several cryptic or sibling species are identified by karyotypic variation (Baker, 1984 ; Baker et aI., 1985) and thi s complex has been used as an empirical basis for a speci atio n mod el (spec iation by mo nobrachi al fusi on s, Baker and Bickham , 1986 ). Some species show little orno morphological distinctiveness (Baker, 1984). For the two most widely distri but ed speci es recognized by morphologica l differenc es (R. tumida and R.parvula), the rang e of geographic vari ation in morph ology within both species is greater than any morphological features that distinguish the two (La Val, 1973). Although, several species h ave been recognized based on kary otypes, the morphological feature s are still problematic when used to identify taxa. One of the karyotypic form s (Ho neycutt et al., 1980 ) from Suriname has been identified as a previously undescri bed species (Ruedas and Bickham, 1992) and this paper present s a formal description of that taxon . Be fo re a formal de script ion can be m ade , so me clarificati on of speci es boundaries and characteristics is needed to permit the required comparisons. This undescribed spec ies is a member of the R. tumida complex in South America. The first point to consider is that other specimens of the R. tumida complex that have been karyotyped from South America have a diploid number of 30. Specimens with this karyotype have been G-banded and cladistically analyzed (Bak er et aI., 1985) using Myotis and Eptesicus
as out groups (Bic kham , I 979a ; 1979b). The results of thi s analysis indicated that th e 2N = 30 cytotype fr om South America and 2N = 32 cyt otype from Nicaragu a represent sister clades identified by three unique centric fu sions (5/1 , 10/4 , and 11/7 using the sta nda rdized GBand karyotyp e f o r ve spertili onid b ats , Bi c kham , I 979a ). Ba sed on the potential complex meiotic figures that would result from hybrids betw een either the 2N = 30 or the 2N = 32 (N icaraguan) cytoty pes and any ot her cytotype found north of South America, it is probable that the 2N = 30 and 32 (N icaragu an form ) hav e speci ated from more northern taxa by monobrachial fu sions (Baker and Bickham, 1986). The senior sy nony m for the 2N = 30 and 32 (N icar agu an f orm ) cytot ype s is R. i o Tho ma s, 1903 , with a typ e locality of Valencia, Carabobo , Venezuela. At this time it seems appropriate to consider the 2N = 30 cytotype and the 2N = 32 (Nicara guan form ) as co nspeci fic becau se there is no ev idence of an isolating mechanism in the chromoso mal or other data . Therefore, the ran ge of R. i o should be recogni zed as the Atlantic versant of Nicaragua south thr ough Panama, and South America including specimens of R. tumida rec orded by LaVal ( 197 3) for Colomb ia , Venezuel a, Trini da d, Gu yana , and Mato Grosso, Brazil. The situation surro unding the Ecuador specimens is unclear (LaVal , 1973 ; Goodwin , 1958 ). La Val examined and figured bacula (197 3, Fig 2, p. 9) for se veral representatives of the R. tumida com-
Pp. 83 - 87, Contr ibutions in Mammal ogy: A Memori al Volume Honoring Dr. 1. Knox Jones , Jr. Museum of Texas Tech Univ ersity, 1996, il + 3t5 pp.
1. KNOX JON ES MEMORIAL VOL UME
84
plex . Three specimens (fro m Veracru z, Tamaulipas, and Chiapas) are from the ran ge of the 2N = 34 cytotypes (w mida , sensu stricto) and these three are more simi lar to each o ther than to any of the re maining bacula that are figured. Three o ther specime ns , th e eastern versant of Nicarag ua , Co lombia , and Venez ue la , are fro m our pro posed range for R. io and these thr ee have unique bacular morp hology unlike that seen in tumida (senso stricto) and these three are more lik e each other than any is like rep resentatives of tumida (se nsu stric to) . To our eye the baculu m of th e sp eci me n fro m Pun a Isl an d, Ec uado r, m ost c losely resembles th e b acul a of R . minutilla. It is interes tin g to n o te th at R . minutilla is a coast al and island form in the xeri c region s of Venezuel a and Colomb ia and the Puna Island locality matches well this eco logical situatio n . Th er efo re , we are un c om fortable assigning th e Ecua dor specimens to a specific taxon and more study is needed . Chro m osoma l dat a fro m bo th R . minutilla an d th e Ec uad o r p opu lat ion sh ould be va lu a ble in es ta blishing the se rel ation shi ps. We thi nk that th ere are ten s pec ies in the gen us Rhogeessa that sho uld be recognize d. Rhogeessa alieni and R. gracilis are the o utliers rel at ive to the other spec ies and R . mira m ay we ll be as distant to the rema ining tax a as are R. alleni a nd R. gra cilis (La Val, 1973 ). The
relationsh ip of alleni , gracilis , and mira to each other and to m ember s of th e R . tu mi da compl e x m e rit s f urt he r study. Withi n wh at we wi ll ca ll the R. tum ida co mplex there are seven species . Rhogeessa tumida is di stribut ed along the Atlantic versa nt of Mexico so uth ward to Ho nduras wh er e it is found on both the Pa ci fic and A tlan tic versants , Rh ogeessa parv ula is di stributed in M exico f ro m S o n o r a to Guerrero a n d Oax a c a . Rhogeessa ge nowaysi is kn own fro m a re st ri ct ed are a in Chi apas, Mexico. The di stribution of Rhogeessa io is as descr ibed above . The 2N = 32B form de scribed by Ba ker et al. (1 985 ) fro m Belize has been show n to occur in Beli ze , north ern Guatem ala, and throughout th e Yucatan Peninsula by Aude t et al. ( 1993). The seni or syn on ym applied t o thi s taxon was Rh ogeessa aeneus Goodwin , 195 8 (Aude t et aI., 1993). Rho geessa minutilla is found alon g th e no rth co as t of South Ame rica on Margarita Is land, Venezuela , and Co lom bia. The spec ies w e are descri bing herein is fro m northeast ern So uth A mer ic a. The geo graphic relationship of these taxa can be seen in Fi gure I and Bake r ( 1984 ). An ov erview of th e geographic di stribution of the tumida co mp lex indi cates tha t areas of sy rnpatrv are unco mmon and parapatry may be the common rela tions hip at species boundarie s. Our wo rking hy po the s is I S that
~l
()- )
R. tumida
-:«:
--;:;'--R. aeneus
o
~
"
~
c::::>e. zone of
R.
'.. overlap
R.
R. minuti/la .
/ " R. 10
-b..f]
~~~~~
Fig. I. Approxi mate geog raphic distribution of the seve n speci es in the Rhogeessa lumida - co mplex . Exac t geog ra phic boundaries and area s of pot ential sym patry betwee n species arc ye t to be fully studied. Reco rds from Brazil and Ecuador arc not show n (see text and La Val. 1973).
GENOWAYS AND BAKER- NEW RHOGEESSA
85
this pattern is the result of speciation of a once wide spread single species and the relationships among species will in most cases reflect geographic associations. When the geographic di stribution of the R. tumida complex is contrasted with that observed for the other vespertilionid gener a such as Myotis, Lasiurus , and Ep tesicus , the pattern seen in Rhogeessa appears exceptional. In the former three genera, sympatry among species is common and examples of parapatry are not well docum ented . The new taxon described below is from Suriname in northeastern So uth America and the species of Rhogeessa that are in a geographic position to hybridize with the new species are R . i o defin ed above and R. minutilla from along the coast of Venezuela and Colombia.
Rhogeessa hussoni, new species Holotyp e.-Adult femal e, skin and skull , Carnegie Mu seum of Natural History no. 63934, from Surin ame: Nickcric District; Sipaliwini Airstrip; obtained on 18 August 1979 by Jane A . Gr oen and Stephen L. William s; original no. Jane A. Groen 1058; special no . TK 10150. Distributioll. -Northea stern South America (Fig . I ). Known with certa inty from only two localities, one in extreme southwestern Suriname in Nickerie District and the othe r from the state of Bahia in northeastern Bra zil. However, the spec imen from Alto Parnaiba, Maranhao , Brazil , reported by Goodwin ( 1958) and LaVal (19 73 ) may best be assigned to thi s spec ies. It is a skin only in the Fi el d Museum with a length o f fo re ar m of 29.5 (Goo dwi n, 195 8) which is lar ger than any R . min willa (Ruedas and Bickham , 1992) and at the upper end of the variation of R. io. On the other hand , measurements for specimens from southern Guyana (LaVal, 1973) are relatively sm all and we cont inue to ass ign them to R. io until more info rma tion, parti cularly karyotypes, are avai lable from this area. Se lected measurements . -The following external measurements (in millimeters) of the holotype follow those of Ruedas and Bickham (1992 ): length of forearm, 30.2; metacarp al of digit 3,29.0; first (proximal) phalanx of digit 4,27 .8; first phal anx of digit 4, 9.3; metacarpal of digit 5, 28.2; first phalanx of digit 5,7.3. Cran ial measurements (in millim eters ) of the hol otype (Fig. 2) and a sub adult female from Bahia, Brazil (CM 100,000 ), aft er Ruedas and Bickham ( 1992) are as follows : breadth of braincase , 5.7 , 5 .5; condylobasal length , 10 .0 , 9.1 ; depth of braincase , 4.7,4 .6 ; greatest length of sku ll, 13.2 , 12.8 ; mast oid breadth, 7.1, 6 .8; length of mandibular toothrow, 5.2. 5.2; length of maxil-
Fig.2 . Dorsal , ventral, and lateral views ofthe crani um and latera l view of the mandible of the fem ale holotype of Rhoge essa hussoni from Sur iname (e M 63934 ). Bar equal s 5 mm .
lary toothrow, 4.7, 4.5; postorbital breadth, 3.2. 3.2: postpalat al length, 4.7, -; width across upper canines, 3X 3.7: width acro ss upper molars, 5.6, 5.5: zyg omatic breadth , 8.9, -. Diagnosis .-D ipl oid number eq ua ls 52 (Fig. 3 ) with a fundamental number of 52 . Size relatively large compared to other South American species of the genus Rhogeessa with a pr op orti onally s ho rt m andibul ar toothrow. Co mpariso ns ---R hogeessa hussoni is d i s t i nguished by having a diploid number 52 from other members of the genus for which the karyotype is known , includingRhogeessa genowaysi 2N=42 , R. parvula 2N=44 , R. io 2N=30,32, R . tumida 2N=34, and R. aeneus 2N = 32. La Val ( 1973) cite s sev eral char acters by which Rhogeessa minutilla an dR. tumida [=io ] can be di st inguished in northwestern Venezuela. The hol otype of R. hussoni fits several of the characters of R. io mor e clo sely than R. minutil/a. Among these characters are lack of a "helmet" on the cranium, postorb ital breadth of 3.2, teeth unworn , and the third met acarpal more than 1 mm shorter than the forearm .
1. KNOXJONES MEMORIAL VOLUME
86
... t'~~. A. .A...
-.
A
•• r, It ft 1
"
,...
n
AI
•••• ••
Fig ,3 , Representative karyotype of the female holotype of Rhogeessa hussoni from Suriname (e M 63934). The first pair of biarmed chromosomes arc assumed to bethe X -chromosomes. This figure is reprinted from Honeycutt et al ., 1980.
Overall size is largecompared to the other two South American species of the genus , R. minutilla and R. io , except that the length of the mandibular toothrow is proportionally and actually shorter than in these two specie s. The external measurements of the holotype exceed the range of variation in a series of nine R. minutilla and l OR. in [under the name tumidai (Ruedas and Bickham , 1992 ) in four of the eight measurements studied including (range for R. minutilla followed by R . io ) metacarpal of digit 3 (25.7-28.0; 26.2-28.4 ), second phalanx of digit 3 (8.7-10 .2; 8.8-10 .0) , metacarpal digit 4 (25. 1-27 .6; 25 .9-2 7.4 ), and metacarpal of digit 5 (26.0-27.9; 26.327.8). The cranial measurements of the holotype exceed the range of vari ation of thes e same series in five of the II mea surements studied including cond ylobasallength (8 7-9.8: 8.5-91 ), greatest length of skull (11.8-12 .9 ; 11.7-12 .6), postpaJatallength (4.1-4.4; 4.0-4.4), width across upper canin es (3.3-3.7; 3.4-3.6), and width across upper mol ars (5.0-5.5; 5.0-5.4 ). On the other hand , the length of the mand ibular toothrow of the holotype is 5.2 whi ch is under the range of variation in these samples (5.3 -6 .0; 5.4-5 .7 ) presented by Ruedas and Bickham (1992) . The specimen examined from Brazil is a subadult female with the ph alangeal epiph yses still clearly open. There is not a kary otype avail able for this specimen, but we ha ve assigned it to R. hussoni because of its short mandibul ar toothrow which is fully erupted . Remarks .-Diploid numbers reported for the Rhogeessa tumida complex are 30 , 32 , 34 , 42, 44 , and 52 (Bickham and Baker, 1977; Baker, 1984; Honeycutt et ai, 1980). When described, five of these values (30, 32, 34, 42, and 52) were reported for what at that time was recog-
nized as a single species, R . tumida. Part of the variation within tumida was removed when Baker (1984) described the 2N = 42 form as R. ge nowaysi. The ju stification for specific distinctiveness of the 2N = 42 form was the sympatric occurrence of the 2N = 42 and the 2N = 34 forms . The 2N = 34 cytotype is widely distributed and includes the type locality of tumida, whereas the 2N = 42 cytotype is restricted to a small geographic region in Chiapas, Mexico. Without chromosomal data , the existence of R. genowaysi would not ha ve been detected, as exhaustive examinations of the two have failed to provide morphological feature s or measurements to distinguish between them (1. K. Jones, Jr., and D. C. Carter, pers. comm .). The description of the 2N = 52 cytotype herein , does not have the clear cut situation established by sympatric occurrence . However, se veral aspect s o f the karyotypic data from South American taxa indicate it is appropriate to describe R. hussoni at the specific level. Over one hundred species of vespertilionid bats have been karyotyped (McBee et al., 1986) and certain pattern s are evident. For this family the primiti ve karyotype is prop osed to be 2N = 44 with a G-band karyotype like that found in most Myotis (Bickham, 1979a , 1979b ). For species with a higher diploid number like Eptesi cus fliS CUS , centric fissions are proposed to have occurred. Such a series of fis sions are required to deri ve the propo sed karyotype primiti ve for Rhogeessa (Baker et al ., 1985 ). Baker et al. (1985) proposed that two biarmed autosomes (the 16/1 7 and the 20/18) and a biarmed X were present in the karyotype primitive for Rhogeessa . They proposed that the 20/18 was a synapomorphy for the genus , however, the 16/17 was primitive for all vespertilionids. Becau se we have karyotyped only a female for R. hussoni and no G-bands ha ve been produced we arc forced to estimate the evolution of the karyot ype fro m nondifferentiall y stained chromosomes. We suspect that the large biarmed element in R. hussoni is the X and the two other s m a l l e r biarmed clements are lik ely autosomes. If one of the small er elements is the 20/18 then other events are required to derive the R . hussoni karyotype from that proposed as primiti ve for Rhogeessa . These events are likely the fission of the 16/17 or 20/18 and the fragmentation of one other acrocentric to elevate the karyotype to a 2N = 52. Perhaps, both the 20/18 and the 16/17 arc fissioned and the two other biarmed autosome s are from pericentric inver sions . Unfortunately, all of this is speculation, but , it is clear that several events are required to produ ce the R. hus soni karyot ype
GENOWAYS AND BAKER- NEW RHO GEESSA
from that proposed as primitive for Rhogeessa and several event s are required to relate the R. hussoni karyotype to that known for any de scribed for an extant species . Therefore , the most con servati ve cour se of action is to describe R. hussoni as a distinct species. In fact , if we were to describe R. hussoni as a subspecies based on the available chromosomal data , we would not know in which recogni zed species to place it. Etymology.- It is our pleasure to name this species in honor of the late Dr. A. M. Husson, the former Curator of Mammal s of the Rijksmuseum van Natuurlijke Historie in Leiden, The Netherlands, in recognit ion of his maj or contributi on s to the s tudy of So uth American mammal s through his monographs on the bats of Suri name (1962) and the mamm als of Suriname (1978). Spe cim ens examined (2).- Suriname: Nickerie District; Sipaliwin i A irstrip I (CM). Brazil: Bahia; FazendaS ao Raimund o, Juazeiro da Bahia, I (C M). ACKNOWLEDGMENTS .-We wo uld particularl y like to thank Dr. Duane A. Schlitter, Carnegie Museum of Natural History (CM), for the loan of specimens for our examination. Our field work in Suriname was supported by a grant from the Alc oa Foundation, Pittsburgh , PA. We would also like to thank Dr. Joop P. Schulz and Henry A. Reich art. STINA SU. for assistance in all phase s of our work in Su riname. Ferdi nand L. Baal, Department of Forestry, issued our permits. Mr. Leo Roberts. STINAS U, proved to be an exce llent field guide and most congenial companion. Stephen L. William s and Jane A. Groen conducted much ofthe field workin Suriname. Laboratory phase s of this work were supported by an NSF grant to Robert J. Baker. Finally. we want to thank John W. Bickham, Meredith J. Hamilton, and J. Knox Jones. Jr., for reviewing a draft of this manuscript.
liTERATURE CITED
Audet , D., M. D. Engstrom, and M. B. Fent on. 1993. Morph ology, karyology, and echolocation calls of Rh ogeessa (Chiroptera: Vesp ertili on idae ) fro m the Yucatan Peninsula. Journal of Mammalogy, 74:498-502.
87
Baker, R. J. 1984. A sympatric cryptic species of mamm al: a new species of Rhog eessa (Chiroptera: Vespertilionidae ). Systematic Zoolog y, 33: 178-183. Baker, R. J., and J. W. Bickham. 1986. Speciati on by monobrachial cen tri c fusion s. Proceedings of the National Academ y of Science, USA, 83: 8245-8248. Baker, R. J., J. W. Bickham, and M. L. Arnold . 1985 . Chromosomal evolution in Rhogeessa: pos sible speciat ion by centric fusio ns. Evolution, 39: 233-243 . Baker, R. J., M. B. Qums iyeh, and C. S. Hood . 1987. Role of chromo somal banding patterns in understanding mammalian evoluti on . Pp . 67- 96 , inCurrent Mamm al o gy ( H . H . Genoways, ed.), Plenum Press, New York, l :xx+I -519. Bickham , J. W. 1979a. Banded karyotypes of II species of American bats (ge nus Myo tis). Cytologia, 44: 19-27 . - - - . 1979b. Chromosomal variation and evolut iona ry relationshi ps o f vespertilionid bat s . Journ al o f Mam mal og y, 60:350-363. Bickham , J. W., and R. 1. Baker. 1977 . Implicati ons of chromosomal variatio n in Rhogeessa (Chiroptera : Vespertil ionid ae). Journ al of Mammalogy, 58:44 8-4 53. Goodwin, G . G . 1958 . Bat s of the genus Rh oge essa. A merican Museum Novitates, 1923: 1-17. Honeycutt , R. L., R. J. Baker, and H. H. Gen owa ys. 1980. Results of the Alcoa Foundation - Suriname Exped itions. III. Chromos omal data for bats (Mammalia: Chiroptera ) from Suriname . Annal s of Carnegie Museum , 49: 237-250. Husson, A. M. 1962. The bats of Suriname. Zoologische Verhandelingen, Rijk smuscum Natuurlijkc Historic, Leidcn. 58: 1282. - - - . 1978. The mammals ofS urinamc. Zoo logi sche Monograph i cn , Rijksmuseum N atuurlijkc Histor ic , Le idc n. 2:xxxiv+1-569 . LaVal, R. K. 1973 . Systematics ofthc genu s Rhogeessa (C hiroptera: Vespertilionidac). Occasional Papers of the Muscum of Natural History, University of Kansas, 19:1-47 . McBee, K., 1. W. Bickham. S. Ycnbutra. J. Nab hitabhata. and D. A. Schlitter. 1986. Standard karyo logy of nine species of' vespcrtil ion id bats (Chiroptcra : Vespertilion idae ) from Thailand . Annal s of Carnegie Museum , 55:95- 116. Rucdas, L. A., and 1. W. Bickham . 1992. Morph ological differen tiation between Rh ogeessa minutilla and R. tumida (Ma mmalia: Chiroptera : Vespertilionidac). Proce edings of the Biological Society of Washington, 105 : 403-40 .
University ofNebraska State Museum, W436 Nebraska Hall, University of Nebraska-Lincoln, Lincoln, NE 68588-0514 .. Department ofBiological Sciences and The Museum, Texas Tech University, Lubbock, TX 79409.
